An electron moves across Earths equator at a speed of 2.5 _ 106 m/s and in a direction 35 N of E. At this point, Earths magnetic fi eld has a direction due north, is parallel to the surface, and has a magnitude of 0.10 _ 10_4 T. What is the force acting on the electron due to its interaction with Earths magnetic fi eld? (a) 5.1 _ 10_18 N due west (b) 4.0 _ 10_18 N toward Earths surface (c) 2.4 _ 10_18 N away from Earths surface (d) 3.3 _ 10_18 N toward Earths surface (e) 4.0 _ 10_18 N away from Earths surface

Current and Resistance An electric current is represented by an arrow which has the same direction as the charge velocity. The sense of the current arrow is defined as follows: 1. If the current is due to the motion of positive charges the current arrow is parallel to the charge velocity v 2. If the current is due to the motion of negative charges the current arrow is antiparallel to the charge velocity v The electric current is the amount of charge per unit time that passes through a surface that is perpendicular to the motion of the charges. One coulomb per second equals one ampere (A). If the charges move around the circuit in the same direction at all times, the current is said to be direct current (dc). I